Evaluation of powdery mildew (Podosphaera pannosa (Wallr.) de Bary) in roses

Roses are one of the main floricultural and decorative crops and are widely used in industrial floriculture and landscape architecture. During cultivation, rose plants are susceptible to various infectious diseases that impair their decorative properties. A common and dangerous pathology is powdery mildew, which is caused by the fungus Podosphaera pannosa (Wallr.: Fr.) de Bary. The study aimed to assess the susceptibility of rose varieties to powdery mildew in Kyiv. The study was conducted at the rose garden of the Hryshko National Botanical Garden of the National Academy of Sciences of Ukraine and in the problematic research laboratory of Mycology and Phytopathology of the National University of Life and Environmental Sciences of Ukraine. The spread and intensity of powdery mildew development were assessed against a natural infection background using a scale that included a gradation from 0 to 4 points. A total of 79 rose varieties from 6 garden groups were examined. During the research, powdery mildew developed during May-October on all aboveground parts of plants (except lignified shoots), but most intensively on young shoots. During the vegetation period (2022-2023) in the open field, among the 17 varieties of the floribunda group examined, the disease did not develop in 12 varieties. The evaluation of powdery mildew on 16 varieties of hybrid tea roses showed its absence on 13. Among the 8 varieties of climbing large-flowered roses, the disease developed in 2 varieties. On roses of the shrub group, the pathology was not widespread in 23 varieties out of 33 studied. All 3 varieties of musk roses were not affected by P. pannosa, while in 2 varieties of ramblers, its presence was noted. In total, the disease was widespread in 22 rose varieties. The study of powdery mildew damage to roses is relevant for the development of control measures and the search for sources of resistance that can be used in the breeding process